Generally, silver (Ag) is known as possessing the antibacterial effect that kills approximately 650 bacteria by stirring up the electron transfer system in the cell membranes outside the bacteria's body, so it is unlikely to create resistant bacteria. Also, since it is not poisonous to human body unlike common organic antibacterial agents, it is applied to many antibacterial agents and other materials using silver.
The demand for antibacterial materials is on the rise as economy booms, the quality of life continues to improve, and consumers pursue healthy and pleasant life. Recently, antibacterial manufacturing has been applied to a variety of textiles from clothing, bedding, interior goods to antibacterial filters, medical textile products, and even to wallpapers, floors, tableware, washing machine, etc. And its application range is getting bigger now.
Korean Laid-Open Patent Publication No. 2004-0003451 discloses the antibacterial agents in which 0.3˜20 nm of silver colloidal particles are dispersed on the concentration of 0.5˜50 ppm. Also, Korean Laid-Open Patent Publication No. 2005-0075905 discloses how to prepare antibacterial functional complex textiles through 20˜70 nm sized silver particles that are dispersed within the island component of a sea-island typed conjugate fiber and then chemically eluted, so that the silver particles can remain on the surface of the fiber. Also, Japanese Laid-Open Patent Publication No. PYUNG2002-293705 discloses the silvery antibacterial agents composed of inorganic adsorbents in which silver colloidal particles and cationic surfactants are embedded.
Korean Laid-Open Patent Publication No. 2005-0121149 discloses how to make antibacterial ceramic products by adding the nanosilver antibacterial agent to the glaze or spraying it on the surface of ceramic products, which are then fired.
However, the former silver antibacterial agent made by precedent technology has a few problems that prohibit it from being used for various products.
Firstly, it is hard to apply silver particles to antibacterial products. For instance, in a trial of fixing silver particles onto the textile surface, the particles are not firmly stuck to it but eventually wearing off due to washing, rubbing, etc., which makes the antibacterial effect deteriorate. When adhesives or resins are used to make up for the weakness, they also fail to induce antibacterial effects from silver, since the silver particles exist inside the adhesives.
Secondly, the nano-sized silver particles are expensive. Although silver has great disinfection power for the size smaller than nano-size, it is uneconomical to be industrialized due to the high cost.
Thirdly, the silver colloidal antibacterial agents which silver particles are dispersed should go through the process where silver particles are uniformly dispersed in solvents. By such dispersion process, the manufacturing cost becomes high and the product stability drops.